Heatstroke in Dogs and Cats

By Deb Haines

Heat stroke is a life-threatening condition characterized by an elevated core body temperature and central nervous system dysfunction. Despite aggressive lowering of core body temperature and treatment, the pathophysiologic changes associated with heat stroke can lead to multi-organ dysfunction, which can be fatal.

Please keep pets out of cars in extreme heat

What Happens to a Heat-Stressed Pet?

During heat stress, the animal’s internal body temperature can increase rapidly, and fatal organ failure can follow. Since dogs and cats do not sweat (except on footpads and the nose) the way humans do, they cannot use this as a method to lower body temperature. Instead, dogs and cats try to regulate their body temperature by panting to help body heat dissipate. This response, however, is limited and easily overwhelmed under extreme conditions.


Unlike humans, dogs have very few sweat glands, limited to the footpads. In moderate conditions where ambient temperatures are below 89.5 degrees Fahrenheit, dogs can often cool themselves effectively via physiologic mechanisms. As temperatures rise, however, dogs rely more on evaporative cooling via panting to dissipate body heat This is made less efficient with increasing environmental humidity. As core body temperature rises, clinical signs of heatstroke may become evident. These include hypersalivation or drooling, increased panting, vomiting, diarrhea, lethargy, and collapse


While all dogs are at risk for heatstroke under certain conditions, some dogs may indeed be more predisposed to heatstroke than others Brachycephalic breeds, or dogs with shortened, “smush” noses such as boxers, pugs, etc. have anatomically restricted airways that may predispose them to heatstroke under even moderately elevated ambient temperatures. Dogs that are obese or suffer from cardiovascular or respiratory disease may also be predisposed. Pediatric and geriatric dogs as well as dark or longhaired dogs are more at risk as well. Of course, external factors also play a role.

Leaving animals in poorly ventilated, enclosed spaces such as vehicles, doghouses, or sheds for even a few minutes may result in heatstroke. Strenuous exercise and muzzling may also rapidly increase core body temperature. Poor acclimation to outdoor conditions may predispose dogs to heatstroke as well. This is especially important to remember in the spring when temperatures are rapidly climbing.


Preventing heatstroke is much preferred to treating heatstroke, and it is very easily achieved. Avoid exercising dogs during extremely hot times of the day. Save walks for early mornings and ate evenings, and be especially careful when exercising brachycephalic breeds. Stop frequently for water breaks and time in the shade. Don’t leave dogs outside or in direct sunlight without access to shade and water. Never leave a dog in an enclosed space such as a shed or a vehicle. Even a few minutes can cause severe, potentially irreversible damage.


If you notice the signs of heatstroke (hypersalivation, increased panting, vomiting, diarrhea, lethargy, or collapse), immediately take your dog to a veterinary hospital or clinic.

Begin active cooling during transportation only if it does not delay travel time. Active cooling involves wetting your dog to the skin with cool, not cold, water. Extremely cold water will only cause the animal to vasoconstrict and thus retain body heat.

Note….“The faster you cool the dog, the better chance he has of surviving,” says Dr. McMichael from university of Illinois “And if you are using water from a hose, be sure that the water is cool before spraying the dog. When the hose has been sitting in the sun, the water may be very hot.”

Note… Roll the windows down in the car to increase ventilation and cooling by evaporation on your way to the veterinarians.. Offer water as soon as possible. If heatstroke is left untreated or if treatment is delayed, it may progress to multiorgan failure. Depending on the stage of the disease and how the animal presents, further supportive care may be necessary.

What are the signs of heat stroke in a cat?

Then, as your cat’s body temperature begins to rise, signs of heat exhaustion become evident, including:

  • Rapid pulse and breathing.
  • Redness of the tongue and mouth.
  • Vomiting.
  • Lethargy.
  • Stumbling, staggering gait.
  • Rectal temperature is over 105° F.




The Vet Corner Groups are run solely by volunteers. If you would like to support the groups, please feel free to make a donation to the running costs of the groups and websites. We thank you for your kindness!

© 2014-2022 Rural Veterinary Outreach. All Rights Reserved.